Thread composition containing ground seed shells



Unite? States Patent Q THREAD COMPOSETIGN CONTAINING GROUND SEED; SHELLS George (1. Howard and Lawrence B. Wilder, Tulsa, Okla, assignors to Pan American Petroleum Corporation, Tulsa, Okla, a corporation of Delaware No Drawing. Filed Oct. 30, 1957,.Ser. No. 693,227

9 Claims. (Q1. 252-47) This invention relates to lubricants. More particularly, it relates to thread compounds for use in pipe joints.

When threaded pipe is screw into threaded couplings, a.

lubricant is generally applied. This lubricant serves not vided particles of malleable metals, such as copper or lead, are added to the thread compound to improve the leak resistance of joints in which the compound is. used.

Even when the best thread compounds are used, leak-.

age sometimes occurs at pressures below the safe working pressures for the pipe. This is generally due to differences. between the taper, depth, or shape of the two threadswhich are screwed together. The problem is particularly serious in pipe with thick walls if the pipe or coupling is not exactly round, but slightly elliptical.

An object of this invention is to provide an improved thread compound. Other objects will be apparent from the following description and claims.

We have found that thread compounds can be greatly improved by the addition of ground hard seed particles. For example, ground black walnut shells may be added to a lithium base grease, or to thread compounds now available, to form. improved thread compounds.

Most plant seeds have some portions. which are fairly hardy and strong. For our purposes, these hard strong portions should be capable of: being ground to. a. granular form passing a Number. 3 0 U.S. standard sieve and preferably passing a Number 100 sieve. For convenience in grinding, the hard plant seed material should have a thickness of at least about 0.04 inch; Thinner shells may be. used in some cases, but. generally are not desirable because of their more fibrous nature, which increases the difliculty of grinding, and because the thinner shells are softer and weaker and many of them tend to soften further upon contact with water or oil. To exclude such soft materials, a minimum limitation of about 5,000 pounds per square inch should be observed in the compressive strength of the hard plant seed materials,

Preferred hard plant seed materials include shells from black walnuts, English walnuts, hickory nuts, butternuts, pecans, coconuts, and Brazil nuts. The preferred hard plant seed materials also include pits from peaches, apricots, cherries, olives, and dates. Other similar hard plant seed materials generally referred to in the industry as shell will occur to those skilled in the art. Some of the thinner, more fibrous. shells can be made to work. These include almond shells, chestnut shells, acorn shells, cottonseed hulls, and the like. This group of thinner shells should be regarded as operable but relatively undesirable alternates to the thicker shells. Other seeds, such as grape seeds, orange seeds, watermelon seeds, peanut hulls, and the like, should not be considered operable. The hard portions of such seeds are too thin, soft, and water sensitive. When reference is made hereinafter to finely divided hard plant seed material it will be understood that reference may be to a single type of material, such as black walnut shells or peach pits, or may be to a mixture. of several types of such hard plant seed materials. Of the shell materials described above, the ones preferred over all the others are black walnut shells and peach pits. These are preferred because they are among the hardest and strongest, are the most readily available in large amounts, and are obtainable at a low cost.

The type of grease to which the finely ground shell is added apparently is not of great importance. If the threads are to be exposed to water, use of water-soluble soaps, such as sodium stearate, in the grease should, of course, be avoided. 'By far the most preferred type of grease is a lithium grease containing about 5 to 10 percent of a lithium soap of a fatty acid, such as stearic acid, in a mineral oil having a viscosity of from about 200 to about 800 seconds as measured by the Saybolt Universal viscosimeter in accordance with ASTM Test D88-53 Other suitable lithium greases, together with several satisfactory methods of preparing them, are described in an article entitled Lithium Greases in The Petroleum En ineer. May 1953. pa e C-l5. The grease may'consist simply of a mineral oil and a suitable soap, or it may contain other additives, such as the finely divided lead, copper, graphite, and the like frequently usedin thread compounds. Other greases, such asvery viscous petroleum fractions free from soaps, may also be used as bases for our thread compounds.

The concentration of finely divided hard plant seed materials, such as black walnut shells, should be between about 10 percent and about 50 percent by weight of the total thread compound; that is, the thread compound should contain between about 50 and about 90 percent grease and between about 50 and about 10 percent finely divided shell materials.

Mixing of the ground hard plant seed material into the grease may take place by any convenient means. Preferably, the finely divided shell material' should be blended into the grease by mixing or milling while the grease is cold. It may, however, be mixed into the grease at elevated temperatures, such as those normally used in grease manufacture. Stirring must, of course, continue in such cases until the viscosity of the composition is sufficient to prevent settling of the solid particles of shell materials.

A preferred thread compound can be prepared by stirring about 30 parts by weight of black walnut shells ground to pass a Number U.S. standard sieve into about 70 parts of a lithium grease containing about 8 percent lithium stearate and about 92 percent of a mineral oil having a viscosity of about 300 seconds. at 100 F. on the Saybolt Universal viscosimeter.

Our invention will be better understood from the following example in which several thread compounds were tested on threads of pipes of various diameters. Each test assembly consisted of a 2-foot length of p pe with a coupling and bull, plug at each end. One plug was tapped to permit application of hydraulic pressure inside the assembly. Reference marks were made with a center punchon the bull plugs and pipe section. The threads were cleaned thoroughly, coated generously with the threadcompound, and all threadsmade up by hand. The pipe was then placed in a lathe, chain tongs were applied to the bull plug, and the pipe was turned by the lathe until the weight of the chain tongs would not prevent turning of the bull plug. The distances from the reference marks to the edges of the couplings were then measured. A weight was next hung on the end of the lO-foot handle of the chain tongs, the pipe was again turned by the lathe until the tongs and added weight would not prevent turning of the bull plug, and the distances from the marks to the edges of the coupling were again measured. The

same procedure was repeated with the bull plug on the other end of the assembly. The number of turns make up by application of the known amount of torque was calculated from the ditference in the distances to the divided hard plant seed material having a compressive strength of at least about 5,000 pounds per square inch.

2. The thread composition of claim 1 in which said grease is a lithium base grease.

reference marks with and without the weight hung on the 5 3. The thread composition of claim 1 in which said end or the chain tongs handle. Hydraulic pressure was finely divided hard plant seed material is black walnut then applied to the interior of the pipe assembly in increshells ground to pass a Number 100 U.S. standard sieve. ments of about 1,000 psi. until a joint leaked. If no 4. The thread composition of claim 3 in which said leak occurred at approximately the safe working presgrease is a lithium base grease. sure of the pipe, this fact was noted. In some cases when 5. The method of increasing the pressure which a a leak developed at a pressure considerably below maxithreaded pipe joint will withstand without leaking commum working pressure, the joints were disassembled, prising applying to the threads of said joint before screwcleaned, new thread compound was applied, and the joints ing together a thread composition consisting essentially of were made up with increased torque. The pressure at from about 50 to about 90 percent by weight of grease which leakage occurred was then again measured. The containing a mineral lubricating oil gelled with a metal results of these tests are presented in the following soap and from about 10 to about 50 percent by weight table. of a finely divided hard plant seed material having a com- Table Pipe Make Up Threads Leak Thread Compound Torque, Make Up Pressure, 0.1)., Weight, Grade ft. lb. 1b.lsq. in. inches lb.

7 26 N-SO Ordinaay thread eom- 5,130 3. 4,000 7 26 N-80 Niigs h ell s in ordinary 5,130 3.50 7,200

thread compound. 1 7 26 N-80 Nutshells in lithium 5,130 3.50 7,200 5% 17 L55 oi d i i's' thread com- 1,645 1.24 5,500 5% 17 J-55 or d r i ry thread com- 2,140 1.76 1NL5, 500 at 17 J-55 Li iiiiiii rmse 490 0.60 500 5g 17 L55 Lithium grease- 1,125 0.82 1,000 5, 17 3 55 Lithium grease 1,645 1.18 3,000 5% 17 L55 Nutshells in lithium 490 0.90 5,500 5%---- 17 7-55 Niii tills in lithium 1,125 1.42 NL5,500

grease.

1 N L means no leak occurred at the designated pressure.

The ordinary thread compound was a lithium base presssive strength of at least about 5,000 pounds per grease containing about 40 percent by weight of a mix- 40 square inch and subsequently screwing said threads toture of copper, zinc, and lead powders. This composition gether to form the joint. was selected for comparison since it had proved superior 6. The method of claim 5 in which said grease is a to other thread compounds in previous tests. The lithium lithium base grease. grease was a standard auto chassis lubricant. The nut- 7. The method of claim 5 in which said finely divided shells in all cases were black walnut shells ground to pass hard plant seed material is black walnut shells ground to a Number 100 U.S. standard sieve. One part of walnut pass a Number 100 U.S. standard sieve. shell flour and two parts of lithium grease were used to 8. The method of claim 7 in which said grease is a prepare the nutshells in lithium grease composition listed lithium base in the table. Only one part of walnut shell flour was 9. A pipe thread composition consisting essentially of used with five parts of the ordinary thread compound about 85% to 90% by weight of alubricating grease consince this compound was already rather thi k and vi ou taining a mineral lubricating oil gelled with a metal soap because of the metal powders present, and about 10% to about 15% by weight Of walnut shells The results persented in the table show that ordinary ground to P a Number 100 Standard Sievegrease containing finely divided hard plant seed material performs better than regular thread compounds contain- References Cited in the file of this patent ing metal powders. The results also demonstrate that or- UNITED STATES PATENTS dinary thread compounds can be greatly improved by adding a little of the finely ground hard plant seed 3- 217791735 Brown at 291 1957 terial. Thus, it Will be apparent that we have accon- 2,800,964 Garnck July 301 1957 plished the objects of our invention. 218111207 Clark 1957 We claim; 2,815,079 Goins et a1. Dec. 3, 1957 1. A thread composition consisting essentially of from about 50 to about 90 percent by weight of grease contain- OTHER REFERENCES ing a mineral lubricating oil gelled with a metal soap, and Lubricating Grease y BOnePReinhOld Pull New York, N.Y., (1954), page 784.

from about 10 to about 50 percent by weight of a finely 

9. A PIPE THREAD CONPOSITION CONSISTING ESENTIALLY OF ABOUT 85% TO 90% BY WEIGHT OF A LUBRICATING GREASE CONTAINING A MINERAL LUBRICATING OIL GELLED WITH A METAL SOAP AND ABOUT 10% TO ABOUT 15% BY WEIGHT OF WALNUT SHELLS GROUND TO PASS A NUMBER 100 U.S STANDARD SIEVE. 